English Grammer Used to - Would

Used to + verb describes a past situation that is no longer true
I used to go scuba diving.
It is best to avoid using ‘used to’ in negative forms or questions although some native speakers do this in informal situations. It is better to use the Past Simple in those situations.

1 A past habit

'Used to' describes something was an old habit that stopped in the past. It shows that there was repetition in the past but it probably doesn’t occur now.

My dad used to do Aikido.
We used to go skiing every winter.
I used to love sushi but I seem to have gone off it now.

2 Facts and generalisations in the past

'Used to' can also describe past facts or generalisations that are no longer true.

Danny used to live in England.
Most people in the south of the country used to be farmers.
Fred used to have a stressful job.
Tess used to be fat. Now she has a great figure.

Used to – Past Simple

'Used to' and the Past Simple can both describe past habits, facts and generalisations but 'used to' is better when an emphasis is required especially if the repetition is the emphasis of the sentence. However with questions and negative sentences Past Simple is preferred.
You used to do ballet.

Did you do ballet when you were young?
You did not do ballet when you were young.

Would (always/never)

Like 'used to' and the Past Simple, 'would' with 'always' suggests an old habit that stopped in the past. Unlike 'used to' or the Past Simple 'would always' suggests a willingness to do the action or amusement and/or annoyance. It can also suggest an extreme habit. The opposite is expressed with 'would never'.

My grandmother would always get me a book for Christmas.
Sarah would always come late to work on Mondays.
Danny would not always come out with us.
Alison would always end up in a relationship with the strangest men.
We would not always go abroad for the summer holidays.

It is important to remember that 'would always' is not the same as ‘used to’ or the Past Simple. Would cannot be used to speak about past facts or generalisations, only past repeated actions.

I used to be painfully shy when I was young. 
NOT I would always be painfully shy when I was young.
BUT I would always be shy when I met new people when I was a young boy. (In this case 'would always' is describing a repeated action – meeting new people)

'Would' can also be used with; constantly, often or simply alone i.e. 'would' but attention must be given so as not to confuse this function with conditional structures.